Env var vs config priority fixing

lib/ansible/constants.py

@@ -22,7 +22,9 @@ import traceback
 
 def get_config(p, section, key, env_var, default):
     if env_var is not None:
-        return os.environ.get(env_var, default)
+        value = os.environ.get(env_var, None)
+        if value is not None:
+            return value
     if p is not None:
         try:
             return p.get(section, key)